The current overwhelming consensus among Earth scientists is that moldavites were formed 15 million years ago during the impact of a giant meteorite in present-day Nordlinger Ries . Splatters of rocks that were melted by the impact cooled while they were actually airborne and most fell in central Bohemia - traversed by the Vltava river (German Moldau) ). As such the glass can be found in the Czech Republic, Austria and Germany...
The total amount of Moldavite scattered around the world is estimated at 275 tons. There are now only fourmoldavite mines that are in full operation in the Czech Republic. It is predicted that in less than ten years from nowcommercial Moldavite mining will come to an end. After this time, there will be virtually no appreciable amount of gem-grade Moldavite left in the ground.
This eveining I've been going through my stones to select out the ammonites cabuchons to show Julie tomorrow. They are cut from the fossiized shells and are shot with brilliant colors.
I looked through several different groupings of stones. And in the process selected a small opal carved owl (cameo like) that I'll start thinking about designing for.
Ammonites are an extinct group of marine inertebrate animals in the subclass Ammonoidea of the class Cephelopoda. (And as I say often, I love cephalopods) These molluscs are more closely related to living coleoids (i.e.octopuses,squid, and cuttlefish) than they are to shelled nautiloiods such as the living Nautilus species.
...the ammonoid cephalopods first appeared in the Devonian (circa 400 million years ago) and became extinct the close of the Cretaceous.
So from a stone that's only 15 million years old to stones that are over a 100 million.